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:: Upgraded Flotation-circuit at BMA’s Gregory Coal Mine
Bateman Engineering N.V. has upgraded the flotation circuit of the coal-processing plant at the Gregory Crinum Coal Mine near Emerald, Queensland, Australia for the BHP Billiton Mitsubishi Alliance (BMA) by replacing the existing conventional circuit with new flotation technology. BMA is Australia’s largest coal producer and a leader in the international coal industry.
The project covered the installation of a flotation circuit comprising five Microcell flotation columns, 4.9m in diameter and 10.5m tall, and a 30m diameter clean-coal thickener.
This flotation circuit, which has increased the yield of coking coal at the mine by approximately 6 %, refines a slurry of the minus 750 µm fraction of the Gregory’s Lilyvale seam to produce a coking coal with an ash content typically around 5.5 % and as low as 4.5 %. The higher quality of the fine coal emerging from the circuit also enables the coarse fraction to be washed in the existing plant at a higher density, increasing the overall yield of the combined coking-coal product.
The clean-coal thickener assists with dewatering and controls the feed density to the existing belt-filter units. The latter were previously designed, installed and commissioned by Bateman Engineering at the mine.
During construction, 240 t of structural steelwork was installed and about 4,500m of piping used, comprising basalt lined and extra strength steel as well as high-density polyethylene (HPDE) piping. Electrical and control systems to run and automate the operation of the circuit were also provided.
The design concept embodied in the project was that the upgraded circuit should work harmoniously with the existing plant and comprise readily-available standard equipment with which BMA was familiar. The focus was on ease of operation and ease of maintenance. The upgrade would also have to be cost effective, with low initial CAPEX and ongoing operational cost.
The project was undertaken under a AUD24 million lump-sum turnkey (LSTK) contract. It presented the usual challenges associated with having to install a new facility alongside an existing operational process plant.
Work on the detailed design for this project commenced in November 2005 and the initial stages were fast tracked to permit the earth works to start and the existing services to be diverted on the site and the off-site fabrication to commence by April 2006. Site work on the structural, mechanical and piping components commenced in July 2006 and the upgraded circuit was successfully commissioned.
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